The subject matter disclosed herein relates to a neutral-hold mode and, more particularly, to a neutral-hold mode for vehicles including a shift-by-wire transmission.
Traditional transmission systems include a mechanical linkage between a gear selector and a transmission. The gear selector may be positioned on a steering wheel shaft, a central portion of a dashboard, or centrally on a console. Mechanical linkages have been used in conventional systems because of design simplicity and reliability. However, shift-by-wire transmission systems have been developed that have advantages over the transmission systems including mechanical linkages.
With advances in digital microelectronics, the control systems available to vehicle manufacturers allow for many configurations and vehicle capabilities that were not possible with traditional mechanical or simple electrical control systems. The new control systems provide a great deal of flexibility and opportunity to produce cars with improved capabilities in terms of performance, safety, and efficiency. However, because modern vehicle control systems are sophisticated computer systems, the manufacturing process requires new solutions to accommodate the complexity of the vehicle control systems. Shift-by-wire transmissions are designed to change gear configurations when an electronic signal is received from a transmission control unit or a gear selection unit controlled by a user. Such shift-by-wire transmissions may include a “return to park” safety feature that does not allow the transmission to remain in neutral after predefined events, for example, after the vehicle ignition is turned off or the driver's door is opened. At different points in the assembly process, it may be beneficial to have the shift-by-wire transmission remain in neutral after the predefined events have occurred.
What is needed is a system that allows a user, such as a worker on a vehicle assembly line, to enter a vehicle in the manufacturing process into a mode that will hold the vehicle's transmission in a neutral gear configuration when other elements of a control system are programmed to shift the transmission into a parked gear configuration. A system and method for holding a vehicle having a shift-by-wire transmission in a neutral-hold mode while minimizing the drain on the battery and preventing other components of a vehicle control system from shifting the transmission into a parked gear configuration is desirable.